Hantfeactith-e-ojy incandescent electric lamps



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FRANCIS HARRISON, OF LONDON, ENGLAND, ASSIGNOR TO THE ALADDIN RENEW ELECTRIC LAM? CORPORATION LIMITED, OF LGNDON, ENGLAND;

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1\To Drawing.

7 '0 all whom it may concern:

Be it known that I, 'FnANors HARRIsoN, a subject of the King of England, residing at London, England, have invented certain new and useful Improvements in theManufacture of Incandescent Electric Lamps, of which the following is a specification.

This invention relates to incandescent electric lamps, itsobject being to provide a simple, inexpensive and rapid method, of re pairing a lamp whose filament has been broken, or which has otherwise become unserviceable. I Y

The commonest type of metal filament incandescent lamp at present in use is the drawn wire lamp containing a central glass stem with two leading-in wires, and several stiff or slender supporting-hooks projecting from "the foot, and several slender flexible molybdenum supporting hooks projecting from a glass knobat the free end of the central glass stem, and it is to the repair or renewal of this type of lamp that this invention relates.

It has already been proposed towind a metal filament on a mandrel so as to form a fine helix or coil of very small diameter, and to mount the resulting filament in an electrio lamp so that it isunnecessary to support at intermediate points filaments of such a length as those usually employed. I have foundby experiment that a tubular coil. of wire of the required dimensionsis particularly suitable foruse in the repair or renewal of unserviceable lamps of the type above referred to. The tubular coiled filament which I employ is prepared by winding a straight tungsten filament on to a stretched wire mandrel of diameter not more than ten times, and preferably about four times, the thickness of the filament wire.

According to this invention the process of repairing or renewing an unserviceable incandescent electric. lamp of the type de-' (b) removing old or broken filaments from the lamp an-dcleaning the interior, if necessary; r

(0') preparing a coiled tungsten filament by winding a tungsten filament of the re-v quired total length. onto asstretohed mandrel of the dimensions specified;

i-peeificationof Letters Patent.

the desired diameter.

'(e) attaching two spring clips, as illustrated in Figure 3 of United States Patent No. 1,247,956 to the leading-in wires'proect1ng from the foot,one clip carrving one end of the filament gripped in it, u

winding the'coiled filament over one or more of the permanent supporting hooks in the lamp, and inserting the otherend of the coiled filament betweenthe turns of the other spring clip;

(g) fusing a glass tube to theedge of the opening in the bulb, and exhausting and sealing the lamp.

In the methods at present in use for renewing lncandescent lampsoffithetype described for example in the British Patent No. lied-64, a number of steps are involved including the preparation of a support for temporary stiff lower hooks, the attachment of this support to'the central glass stem, the I windingofthe filament on to the temporary the filament,

One method of carrying out this invention is now 'described byway of example and as applied to the repair ofan incandescent lamp of theordinary type whose fil ament has been broken. A lamp, the filament of which was o't the ordinary straight uncoiled wire arrangedin zig-zag formation, but whose filament has become broken is taken and an opening made ingthe pip end 111 the known manner, such for example 'as is employed inthe method of United States Patent No. 1,247,956.

Patented May 16,1922. Application filed July 8, 1819. Serial No. 309,885. i

from the tem-' Tungsten wire of the same diameter as that of the original broken filament, and a length .about,l0% greater than that of the original filament is taken and coiled into a tubular coil whose diameter is six times that of the wire. The coiling is carried out cold and directupon a. stretched wire mandrel of To facilitate its removal from the mandrel, the latter lubricated with graphite, be wound slightly open, itself or the coil may and be closed upon during wlthdrawal from the mandrel.

may be filament is slung Internal diameter of Diameter of filament. SpiraL .018 m.m. to .027 m.m. .05 m.m. .028 m.m. to .040 m.m. .08 m.m. .O4l1n.m. to .120 m.m. .13 m.m.

In practice the stretched wire mandrel is composed of a drawn tungsten wire, and as a coating of graphite has been used on the wire during the drawing operation, the required lubrication of the surface is thereby furnished. The wire mandrel, being held in a lathe or wire-winding machine, is rotated on its own axis while the tungsten wire for the filament is wound on to it. The coiled filament thus prepared is obviously of much shorter length than the length occupied by the original straight-wire filament. iently stretched until the length of the coil is that required for insertion in the lamp.

. The filament having been thus prepared and the bulb of the lamp having been subjected to the usual preliminary processes which form no part of this invention, the between the leading-in wires of the lamp and one or more of the permanent hooks, .but owing to its relatively short length it only occupies a small proportion of the said hooks. Its extreme flexibility enables it to be wound direct on to the permanent lower hooks, which are usually of molybdenum, thus avoiding the necessity heretofore regarded as inevitable, of employing stiff temporary hooks, or a former, for the operation of setting the filament. The strength and physical formation of the filament, moreover, are such that it can hang inloops of the usual length supported like an ordinary Zig-zag filament and be properly incandesced, without sagging away from the usual lower hooks. An incidental advantage arises from the fact that the coiled filament gives a better distribution of light and pan ticularly in a downward direction when the lamp is hanging by its cap so that the useful candle-power of the lamp is greater than it was with the original filament. Fun thermore, the increased length of wire employed, namely about 10% greater than that of the original filament, affords a slight increase in the candle-power as compared with the lamp with its original filament.

It is to be understood that the precise rela tion of the diameter of the coil to the thiclo ness of the wire may be varied provided always that the physical formation obtained is such that the filament can be supported in the manner of an ordinary zig-zag filament without sagging away from its supports in use, but the following dimensions have been found by experiment to be successful 2- A further advantage arising from a fila- This closely wound coil is conven-' ment having the proportions provided by this invention is that it enables a much greater length of wire to be inserted in a given lamp than can be employed as a straight-wire zig- Z'ag filament. This provides a ready means for repairing a lamp originally constructed for one voltage, in such a way as to be employed upon a higher voltage; indeed it has been found that a lamp originally wound for sixteen volts can be repaired with a filament according to the present invention so as to be used upon a 100 volt circuit. In carrying such a change into effect the requisite length of wire for the higher voltage is prepared in coiled form and the length of the coilis then simply and readily adjusted by stretching it so that it shall correspond with a con venient number of zig-zag loops to extend from one leading-in wire to another.

It may occur in many cases that some of the original supporting books of the lamp may not be required for the support of the coiled filament. It is, of course, a simple matter to nip these extra supports off during the repair, but I prefer to leave the extra supports as spares to be utilized if the lamp is renewed again, or in case that a support in wire breaks during repair.

lVhat I claim as my invention and desire to secure'by Letters Patent is 1. The method of renewing metal filament lamps having permanent supporting hooks arranged therein in independent series located in different planes, comprising making an opening in the lamp bulb, removing the old filament therethrough and forming a new filament of a series of coils, and apply ing said new filament to any desired number of said hooks by stretching same to the desired length, substantially as described.

2. The method of renewing metal filament lamps having permanentsupporting hooks therein, comprising making an opening in the lamp bulb, removing the old filament through said opening, forming a new filament of a continuous series of coils, and applying said new filament to any desired number of said hooks by stretching the same to the desired length, substantially as described.

3. v The method of renewing metal filament lamps having permanent supporting hooks therein, comprising making an opening in the lamp bulb, removing the old filament through said opening, forming a coiled filament whereof the diameter of its turns is not more than ten times the diameter of the wire from which it is formed, and applying said coiled filament to any desired number of said hooks by stretching the same to the desired length, substantially as described.

In testimony whereof I afiix mysignature.

FRANCIS HARRISON. 

